Dynamic-braking controller.



C. T. HENDERSON.

DYNAMIC BRAKING CONTROLLER. I APPLICATION man on. 14. 1913. 1 1 34 1 97 Patented Apr. 6, 1915.

2 SHEETS-SHEET 1.

W mmmy C. T. HENDERSON.

DYNAMIC BRAKING CONTROLLER.

APPLICATION FILED QCT. I4, 1913.

Patented Apr. 6, 1915.

2 SHEETS-SHEET 2.

l v wk 6 A1 V A F0 F0 PU A 3 7 A AI 1 r AL. vW W V 7 J 1 6 A V r s a n w .4 A r. V 1 um 8 h I 1 6 m/ \5 g 4 JA} 6 5 s 6 6mm Mam t 1 OLARK T. HENDERSON, OF MILWAUKEE, WISCONSIN, ASSIGNOR TO THE ED STATES PATENT OFFICE.

CUTLER HAMMER MFG. 00., OF 'MILWAUKEE, WISCONSIN, A CORPORATION OF WIS- CONSIN.

To all whom it may concern:

Be it known that I, CLARK T. Hnnnnnson, a citizen of the United States, residmg at Milwaukee, in the county of Milwaukee and found that the variation in resistance of the Stateof Wisconsin, have invented new and useful Improvements in Dynamic-Braking Controllers, of which the following is a full, clear, concise, and exact description, reference being had to the accompan ing drawing, forming a part of this speci cation.

My'invention relates to improvements in dynamic braking controllers for alternating current motors. v

t is particularlyapplicable to controllers such as that illustrated in my co-pending application, Serial No. 520,128, filed Sept. 29,- 1909, and other controllers wherein the stator of the .motor is connected to a source of direct current for dynamic braking, and wherein the dynamic braking action is regulated by variation ofresistance in a rotor circuit. In such controllers it has been rotor circuit and consequent variation of the rotor current reacts upon the stator and.

tends to distort and destroy the field produced by the direct current excitation, with the result of effecting the dynamic braking action to an undesirable degree in some cases.

My invention has among itsobjects to provide means for automatically varying the power supplied to 3 the .stator as the resistance in the rotor circuit is varied and thereby maintain the efliciency of the dynamic brake.

1 Other objects and advantages of my invention will hereinafter appear.

In order to more fully and clearly disclose the nature and advantages ofmy in-' vention I shall describe the embodiments thereof illustrated in the accompanying drawings, in which it has been applied to controllers substantially the same as that disclosed in my co-pending application aforesaid. It should be understood, however, that my invention might be applied to other forms of controllers and that certain features thereof might be embodied in other forms than that illustrated.

In the drawings, Figure 1 shows a controller wherein the stator excitation is regulated by means interposed between it'and the source of supply; Fig. 2 shows a controller wherein the stator excitation is regummamo-nnaxmo CONTROLLER.

energizes switches 4 an Patented Apr. 6, 1915.

lated by direct regulation of the supply source.

The controller shown in Fig. 1, like the controller disclosed in my co-pending application, aforesaid, is provided with switches for connecting the stator of the motor to either an A. C; circuit for runnin or a D. C. circuit for dynamic braking an with other switches for regulating resistance in the rotor circuit for acceleration and dynamic braking. I I The motor is diagrammatically illustrated as provided with a stator S anda rotor R. Electro-responsive switches 1, 2, and .3 are provided for connecting the stator to an alternating current circuit A. (3., while electro-responsive switches 4 and 5 are provided for connectingthe stator to a direct .current circuit D. C. Electro-responsive specifically described. The master switch 9 i when moved in one direction energizes switches'l, 2, 3, 6, 7, and 8 for starting and accelerating the motor in the usual way. I

\Vhen moved in an op, osite direction it 5, to connect the stator to th D. C. circuit for dynamic braking, and also controls the switches 6, 7 and 8 to vary the resistance in the rotor circuit and thereby vary the dynamic braking action of the motor. The switches 2 and 4 are provided with auxiliary contacts 10 and 11 respectively, included in circuit with the operating winding and the switches 6, 7 and 8, whereby said latter switches can only respond when one of the former switches is closed to connect the stator to the stator when all resistance in the secondary circuit is short-circuited, 'or when the load is being permitted to descend at'the mini- V the resistance for thestator of avalue sufli cient to give the desired range of potential variation, and to vary the same m steps equal in number to the steps of variation of the rotor resistance. Also, I preferably connect the controlling switches ofthe two sets of resistances for simultaneous operation. Such an arrangement is illustrated, the switches 12, 13 and 14 being operatively connected to the switches 6, 7 and 8 respectively. Thus one section of the stator resistance is inserted in circuit simultaneouslywith the insertion of each step of the rotor resistance. Accordingly as the rotor resistance is inserted in circuit the excitation of the stator is reduced to a predetermined degree to compensate for the variation in the reaction of the rotor upon the stator, thereby maintaining the desired electrical conditmns for dynamic braking' The circuit connections of the controller are obtained aS follows: The switches 1, 2,

. line.

and 3 when closed connect one terminal of the stator by conductor 20 through switch 1 to the left hand supply line of the A. C.

circuit, a second terminal by conductor 21.

and 22 through switch 2 to the center supply line, and a third terminal by conductor 23 through switch 3 to the right hand supply The switches 4 and 5 when closed complete a circuit from the left handside of the D. 0. supply circuit by conductors 24 and 25, through resistances 1' 1' and r in series by conductor 26, through switch 4, by conductors 27 and 21, through stator by conductor 20, through switch 5 to the right hand side of the D. C. circuit. The circuit of the rotor extends from the three terminals thereof by conductors 28, 29 and 30, through thesets of resistances 1', 1" and 'r? to a common connection 31. The switch 6 is adapted to short circuit the resistance r through its contacts a and band conductors 31, 32 and 33. The switches 7 and 8are adapted to shortcircuit the resistances 9" and r by similar contacts and conductors.

- The master switch 9 is adapted to control the energizing circuits of the several switches through contact fingers 40, 41, 42, 43, 44, and'45 and two'sets of coiiperating contact segments. A segment 40 is provided for continuous contact with the finger 40. The

two sets of segments cooperating with' fingers 41 to 45 are disposed on opposite sides thereof. One set includes segments 41, 43, 44 and 45 while the other set includes'segments 42 43 44 and 45 The (1 segments when thrown into engagement with their corresponding fingers energize switches 1, 2', 3, 6, 7, and 8 for running while the b f into engagement with their respective fingers. This first completes a circuit from the left hand side of the D. C. circuit by conductor 46 to finger 40 and segment 40 to segment 41 and finger 41 by conductor 47 through the operating windings of switches 1, 2 and 3 in parallel to conductor 48 and thence to the right hand side of the D. C.

circuit. The switches 1, 2 and 3 are thereupon closed, connecting the stator to the A. (J. circuit as already described. Continned movement of the controller then successively establishes circuits from segment 40 through the se ments '43, 44 and 45 to ductors 49, 50 and 51 to the operating windings of switches 6, 7 and 8 respectively.

These windings hav e a common return by conductors 52 and 53 through the auxiliary switch 10 of switch 2 by conductors 54 and 55 to the left hand side of theD. C. supply circuit. The switches 6, 7 and 8 thereupon respond successively to short-circuit theresistances r, r and r from the rotor circuit.

Assume now that controller be moved to enga e b segments with the fingers 42 to 45. witches 1, 2, 3, 6, 7, and 8'are first deenergized. Then a circuit is closed from segment 40 to segment 42 and contact finger 42, by conductor 56, through the coils of switches 4 and 5 in parallel to the left hand side of the D. C. supply circuit. Thereupon said switches respond, thereby connecting the stator to the D. C. circuit, as above described. At the same .time the operating windings of the switches 6, 7, and 8 are all connected .tothe D. C.- circuit by the segments 42", 43 and 45", and their return circuit is completed immediately upon closure of. switch 4. This return circuit then extends from conductor 52, by conductor 60, through theauxiliary contact 11 of switch 4, by conductor 61 to conductor 55 and thence tothe left hand side of the D. C. circuit. Accordingly all three of the switches 6, 7, and 8 respond immediately upon closure of switch 4, thereby short-circuiting the resistances r, 1" and r in the rotor circuit. As above set forth, the switches 12, 13 and 14 close simultaneously with the switches 6, 7 and 8 and accordingly short-circuit theresistances r 1' and r in the stator circuit. If now the controller 9 be moved f;arther in the same direction it will successively disengage the segments 45,

M and 43 from their corresponding contact fingers, thereby successively deinergizing switches 6,5, and 8 with the result of gradually inserting the resistances in both the rotor circuit and the'stator circuit.

The controller shown in Fig. 2 is similar to that shown inFig. 1, with the exceptions I hereinafter'noted and for simplicity of illustration the operatingwindings of the several switches, the control circuits thereof and the master switch have been omitted. In this controller the direct current excita-' tion of-the stator is provided for by a generator G driven'by a motomM, supplied with current from the A. C. circuit. The generator G is of the shunt wound type, being provided with a shunt field winding F having connected in series therewith resistances 1', 1' and 1' arranged and controlled similarly to the resistances 1', r, and r of the controller shown in Fig. 1. The insertion of resistance in the field circuit of a shunt generator reduces the output of the generator and accordingly the controller as described in connection with Fig. 1 will gradually weaken the field of the generator G upon insertion of resistance in the. rotor circuit and thereby reduce the potential impressed upon the stator-winding. It thus afi'ects the same result as that described in connection with 1. n this controller the switches 4 and 5 connect one terminal of the stator by conductors 61 and 62 to one terminal of the generator G and a second terminal of the stator'by conductors 63 and 64. to the opposite terminal of the generator. The field circuit of the generator extends from conductor 64 through the field winding by conductor 65 through theresistances r", r", and 1' by conductor 66 to conductor 62. The remaining circuit connections are the same as those illustrated in Fig. 1.

What I claim as new and desire to secure by Letters Patent is: i '1. The method of controlling an alternatingcurrent motor for dynamic braking consistlng 1n exclting its stator from a source of direct current and simultaneously regulating the rotor circuit and varying the excitation'of the stator. 2. The method of controlling an alternating current motor for dynamic braking consisting in exciting the stator from a source of direct current and varying the excitation of the stator and the resistance of the rotor circuit to corresponding degrees.

3. The method of controlling an alternating current motor for dynamic braking con.-

sisting in exciting the stator by. direct'current and varying the excitation of the stator and the resistance of the rotor circuit simultaneously and to corresponding degrees.

4. In a dynamic braking controller for alternating current motors, in combination,

means for supplying the stator of the motor with direct current, means for regulating the dynamic braking current generated in the rotor circuit, and means for varyingthe current'supplied to the stator, said last two mentioned means being interlocked to operate together.

5. In a dynamic braking controller for alternating current motors, in combination, means for connecting the stator to a source or. direct current, means for varying the resistan ce of the'rotor circuit to regulate the dynamic braking'action, and means for decreasing the current supplied to the stator upon increase of the resistance of the rotor a circuit.

6. In a dynamic braking controller for alternating current motors, in combination, means for connecting the stator of the .motor to a source of direct current, means for varying the resistance of the rotor circuit to regulate the dynamic braking action, and

means operated by said second-mentioned means to vary the direct current excitation of the stator substantially simultaneously -with the variation of the rotor resistance.

7. Ina dynamic braking controller for alternating current motors, in combination,

means for connecting the stator of the mo tor to a source of direct current, means for varying the resistance of the rotor circuit toregulate the dynamic braking action, and means operated by said second-mentioned means to vary the direct current excitation of the stator substantially simultaneously with the variation of the rotor resistance,-

, alternating current motors, in combination,

means for connecting the stator to a source of direct current, a resistancefor the rotor circuit, means for varying said resistance in steps to regulate the dynamic braking action, and means. operating with said former means to vary the current supplied to the stator to different degrees propor-' tional to the variations of said resistance, said.'last-mentioned means affecting a reduction in the current of the stator circuit uponinsertlon ofsaid resistance in the rotor circuit.

10. In a dynamic braking controller for means for connecting the stator of'the motor to a source of direct current, a resistalternating currentmotors, in combination,

ance for the rotor circuit, a second resistance controlling the excitation of the stator, and means for simultaneously varying said resistance.

11. In a dynamic braking controller for alternating current motors, in combination, means for connecting the stator of the motor to a source of direct current, aresistance for the rotor circuit, a second resistance controlling the excitation of the stator, and means for simultaneously varying said.- resistances, to decrease the stator excitation upon increasing the resistance in the rotor circuit. i

12. In a dynamic braking controller for alternating current motors, in combination, means for connecting the stator of the motor to a source of direct current, a resistance for the rotorcircuit, a resistance for varymg the D. G. excitation of the stator and a plurality of electro-res'ponsive switches controlling said resistances to decrease the stator excitation upon increasing the resistance in the rotor circuit.

' 13. In a dynamic braking controller for.

means for connecting the stator of the mo;

tor to a source of direct current, resistances for the rotor circuit, a resistance controlling nesses.

CLARK T. HENDERSON. Witnesses:

- F. H. HUBBARD,

Tam BART. 4'

2b. alternating current motors, in combination, 

